Success!! I am writing this from my newly restored PC.
Method #2 finally worked. The problem was, the Windows Media Installation tool is apparently a fragile thing. Even though it says something like "verifying download", the download was for me corrupt the first two times. Today I downloaded it again onto three different drives. Finally, one of them worked.
But the new Win 10 installation lost all of my personal files. Thankfully, I had hired a data recovery service earlier, so I didn't lose any data.
The total bill for this adventure was,
$499 ... Data Recovery Service
$57.89 ... 1 TB USB drive for Data Recovery
$300 ... 12 hours of my time (cheap @$25/hr)
$99 ... lost use of the computer for 33 days
$955.89 TOTAL - THANKS, MICROSOFT!!
Thanks, Microsoft. Your screwup cost this customer $556.89 direct cash, and nearly $1000 overall.
My suggestion for anyone who is trying Method #2 ... if it doesn't work the first time, use the tool to download Win-10 again, onto a different disk, and keep trying until it does.
Reinstalling with boot media won't lose any data files unless you format the drive. Of course, for some applications, it won't be possible to just reinstall the application and marry it back to the original data files even if you have them.